Recently it has been found that certain complexes of late transition metals, such as Ni, Pd, Fe, and others are effective catalysts for the polymerization of various olefins, such as ethylene, propylene, higher .alpha.-olefins, norbornenes, cyclopentenes, and others, and copolymers thereof. In some instances olefins containing polar groups such as esters may also be copolymerized. Descriptions of many of these polymerizations will be found in World Patent Application 96/23010, and U.S. Pat. No. 5,714,556.
While some of these complexes may by themselves be able to polymerize such olefins, more commonly a cocatalyst, particularly an alkylaluminum compound, is also added to the polymerization to form an active polymerization system. Typically these cocatalysts have been alkylaluminoxanes (especially methylaluminoxanes), dialkylaluminum chlorides, and trialkylaluminum compounds. Sometimes, and particularly with trialkylaluminum compounds a second cocatalyst, such as another Lewis acid, is also added. While alkylaluminum compounds are effective cocatalysts, they often suffer from one or more drawbacks, such as relatively low catalyst productivity and/or rates, poor catalyst stability, and/or the need for relatively high amounts of the alkylaluminum compound in order to obtain good polymerization rates and/or catalyst productivity. Therefore catalysts systems which are overall improved are desirable.
The use of various alkylaluminum compounds as cocatalysts for the polymerization of olefins using various early transition metal catalysts such as Ziegler-Natta-type catalysts and metallocene-type catalysts is well known. Among the alkylaluminum compounds which have been used for such cocatalysts have been alkylhaloaluminoxanes such as diethyldichloroaluminoxane.
L. A. Volkov, et al., Vysokomol. Soedin., Ser. B, vol. 15, p. 455-457 (1973) report the use of bis(ethylchloroaluminum)oxide as a cocatalyst (with other cocatalysts) for the polymerization of 1,3-butadiene using a CoCl.sub.2 (pyridine).sub.2 complex. The use of bidentate ligands is not mentioned.
Netherlands Patent Application 66/04717 reports the polymerization of butadiene using cobalt tris(acetylacetonate) and bis(ethylchloroaluminum)oxide as a cocatalyst. The use of neutral ligands is not mentioned.
U.S. Pat. Nos. 5,714,556 and 5,866,663 describe the use of various polymerization processes using various late transition metal complexes as catalysts, together with various alkyaluminum compounds as catalysts. The use of alkylhaloaluminoxanes is not specifically described, and the polymerization processes described herein with haloalkylaluminum compounds are also not specifically described.